The present invention relates to a sorting device for fastening components having heads, particularly screws, moving on a conveying device.
Known is a sorting device wherein the screws to be sorted are transported on a conveyor band past an optoelectronic sensor, particularly past a row of CCD-sensors equipped with photodiodes. By means of a projection lamp, a shadow of respective screws is projected on the sensor and the shadow image is compared with desired or standard dimensions. When the projected shadow contour of the screw shows a defect, the resulting error signal activates a group of nozzles which blow off the screw from the conveyor belt. This prior art sorting device has the disadvantage that during the gauging the projected shadow can be tested in single plane only. Consequently, defects on the non-projected circumferential portions on the end surface or in recessed parts (in the slot configuration) cannot be recognized. Moreover, the measuring accuracy is dependent on the conveying speed at the measuring point and on the stable position of the screw on the conveyor band.